My first vector problem

Geometry Level 5

If [ b c d ] = 48 [b\quad c\quad d]=48 and ( a × b ) × ( c × d ) + ( a × c ) × ( d × b ) + ( a × d ) × ( b × c ) + k a = 0 (a\times b)\times (c\times d)+(a\times c)\times (d\times b)+(a\times d)\times (b\times c)+ka=0 then find value of k k

Details and Assumptions

a . b . c . d a.b.c.d are vectors.

[ a b c ] [a\quad b\quad c] is scalar triple product .

x × y x\times y is cross product of x x and y y .


The answer is 96.

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2 solutions

Prakhar Bindal
Aug 8, 2016

JEE Style

Since it is true for a,b,c,d

take b = i , c = 6j , d= 8k and a = i

To get answer in a line

Great Method Bro

Anubhav Tyagi - 4 years, 9 months ago

But I have a better one.................. and that is.................. learn the result

Anubhav Tyagi - 4 years, 9 months ago

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I Dont have Memory like you!. so i had to search for another Short and sweet approach

Prakhar Bindal - 4 years, 9 months ago

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ha ha ha :)

Anubhav Tyagi - 4 years, 9 months ago

@Tanishq Varshney areyou a rollins fan

Anubhav Tyagi - 4 years, 9 months ago
Shubham Rustagi
Nov 30, 2016

my first solution first read it all

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